Finally getting where I can replicate problems with stockquotes phase3 tutorial

I've been going back and forth a number of times and I can now replicate 
issue.

Details: running Debian Linux beaglebone 3.8.13-bone47 #1 SMP Fri Apr 11 
01:36:09 UTC 2014 armv7l GNU/Linux
on a Beaglebone Black C.
Pyro4: 4.31

1) Tutorial works fine with serpent serializer.

2) I have not spent time to figure out if I need to set environment 
variable SERIALIZERS_ACCEPTED
in all three terminals or just in terminal with stockmarket.py, or in 
both terminals with stockmarket.py and aggregator.py, but for tests, I 
am setting in all three terminal windows to be sure. (actually see j 
below - I did spend some time and it appears only terminal 0 needs the 
environment variable). I also change
Pyro4.config.SERIALIZER = 'pickle'
Pyro4.config.SERIALIZERS_ACCEPTED.add('pickle')
in all three files

3) Note: even with serpent, tutorial does not work with
     Pyro4.config.COMMTIMEOUT = 4.0
I believe problem is with aggregator.py and error message is not getting 
enough data (probably from viewer.py)

4) After running successfully with serpent, and going back to running 
with pickle;
a) I stop all programs including name server.
b) I set environment variables in all three terminals
c) I change all three files to pickle
d) I start name server in terminal '0'
e) I run >python stockmarket.py & in terminal 0 and get the error 
message in the terminal
 > /usr/local/lib/python2.7/dist-packages/Pyro4/naming.py:211: 
UserWarning: Pyro protocol error occurred: message used serializer that 
is not accepted: 4
   warnings.warn("Pyro protocol error occurred: " + str(x))
d) I kill python stockmarket.py
e) I try running a second time, now no error message
f) I kill python stockmarket.py
g) I run again under winpdb and find it has hung in core.py, line 327 
waiting to get a threading.Lock(). The lines are:
     def _pyroRelease(self):
         """release the connection to the pyro daemon"""
         with self.__pyroConnLock:
it hangs on the last line.
h) The stack is (in reverse order and short-form)
stockmarket.py: 70, 79 (note, I added some lines to attach to winpdb)
naming.py: 365
core.py: 231, 475, 466, 483, 398, 327

i) I carefully go  back to serpent everywhere, and verify it is working 
again.
j) I unset environment variables in terminals 1 (i.e. aggregator.py) and 
2 (i.e. viewer.py); tutorial 2 still works, it appears the environment 
variable may only be need for the name server/ server terminal.

Summary:
In my board, there is a hanging problem when trying to acquire a 
threading lock when pickle is used as the serializer. serpent works fine 
as long as
communication time-outs are not used.

I hope this helps.
Bit_Pusher



------------------------------------------------------------------------------
Dive into the World of Parallel Programming! The Go Parallel Website,
sponsored by Intel and developed in partnership with Slashdot Media, is your
hub for all things parallel software development, from weekly thought
leadership blogs to news, videos, case studies, tutorials and more. Take a
look and join the conversation now. http://goparallel.sourceforge.net